30 Python Language Features and Tricks You May Not Know About

http://sahandsaba.com/thirty-python-language-features-and-tricks-you-may-not-know.html

the Invisible Man is in your spreadsheet, messing with your data | School of Data - Evidence is Power

http://schoolofdata.org/handbook/courses/data-cleaning-invisible-man-in-spreadsheets/

Easy and clean - Regular Expressions

http://qntm.org/files/re/re.html

Best way to Learn R - Code School - Try R

http://tryr.codeschool.com/

learnpythonthehardway.org/book/

http://learnpythonthehardway.org/book/